barisan aritmatika u5=7 dan u8=10 berapakah u 2

Un = a + (n - 1) b

U5 = a + 4b = 7
U8 = a + 7b = 10

a + 4b = 7
a + 7b = 10
__________-
-3b = -3 
b = 1

a + 4b = a + 4(1) = 7
a = 3

U2 = a + (2 - 1)b = 3 + (1)1 = 3 + 1 = 4